Dishwasher



Filed Jan. 17, 1955 Maf.

H. E. KARIG DISHWASHER 3 Sheehs-SheerI 1 5y Ms rme/vfys.

Dec. 22, 1959 H. E. KARIG DISHWASHER Filed Jan. 17. 1955 Ilma? .6j/VMSrraPA/Eys.

Dec. 22, 1959 Filed Jan. 17, 1955 H. E. KARIG 2,918,068

DISHWASHER 3 Sheets-Sheet 5 ffaqc's Kme/6,

States DISHWASHER Application January 17, 1955, Serial No. 482,239

8 Claims. (Cl. 134-99) The present invention relates in general todishwashing and, more particularly, to a novel method of and apparatusfor drying dishes after washing and rinsing, the term dishes includingdinnerware, tableware, glassware, and other objects.

Primary objects of the invention are to provide a method of andapparatus for drying dishes which avoids contamination of the dishes byforeign matter in the air and which avoids the discharge of moistureinto the room or other area in which the apparatus is disposed.

More particularly, a primary object is to dry the dishes withoutexposure to the atmosphere surrounding the apparatus so that the degreeof sterility and cleanliness attained during washing and rinsing of thedishes is maintained throughout the drying thereof. In conventionaldishwashers, the dishes are dried either by merely opening the door ofthe dishwasher to expose the dishes to the atmoshpere, or by propellingthe ambient air through the dishwasher and over the dishes therein todry them. In either event, the degree of sterility and cleanlinessattained during washing and rinsing is not maintained during the dryingoperation due to the fact that the dishes are contaminated by bacteria,dust, and the like, in the ambient air brought into contact therewith.Such disadvantages of prior dishwashers and prior practice are avoidedby the present invention, which is an important feature thereof.

Considering the invention more specifically, the foregoing primaryobject of the invention is attained by drying the dishes in a closeddish chamber into which no ambient air is introduced after washing andrinsing, thereby permitting the maintenance of a high degree ofsterility and cleanliness during the drying operation.

Still more specifically, an important object of the present invention isto wash, rinse and subsequently dry the dishes in a closed dish chamberto which substantially no ambient air is admitted during the washing,riding and drying operations so that the degree of sterility andcleanliness attained during the washing and rinsing operations ismaintained into and throughout the drying operation.

The foregoing objects of the present invention are attained bycirculating the air in the dish chamber first over the dishes thereinand then over the inner surfaces of the walls of the chamber, whilemaintaining the temperature of the chamber walls below the temperatureof the air circulating in the chamber, so that any moisture evaporatedfrom the dishes in the chamber is conveyed to the inner surfaces of thechamber Walls by the air circulating in the chamber to be condensedthereon, the air dried by condensation on the chamber walls in thismanner being again circulated over the dishes to evaporate furthermoisture therefrom. Thus, the air in the dish chamber is continuouslyrecirculated until all of the moisture has been evaporated from thedishes, such moisture `being condensed on the chamber walls andsubseguently draining to the bottom of the chamber, from whence it isdrained off in any suitable manner. Thus,

2,918,068 Patented Dec. 22, 1959 the invention permits maintaining thedishes in the same condition of sterility and cleanliness as produced bythe washing and rinsing operations, which is an important feature.

As hereinbefore indicated, another primary object of the invention is toprevent the discharge of vapor from the dishes during drying into theroom or other area in which the dishwasher is disposed. Thus, moisturecondensation on windows, walls, and other surfaces, in the room in whichthe dishwasher is disposed, is avoided, which is an important feature.This feature of the invention is inherently attained by drying thedishes in the manner hereinbefore set forth, all of the moistureevaporated from the dishes being condensed within the dlsh chamber andbeing drained off to a suitable point of disposal, such as a sewer line,to prevent condensation within the room in which the dishwasher islocated.

Another object of the invention is to provide means for circulating theair in the dish chamber during drying which includes air heating meansfor maintaining the air in the chamber at an elevated temperature andfor circulating the air through the chamber by convection, the heatingmeans being centrally located at the bottom of the chamber so that theheated air is circulated upwardly through the center of the chamber andthen outwardly and downwardly over the chamber walls back to the heatingmeans. As the air is moved upwardly through the center of the chamber byconvection, it evaporates moisture from the dishes and, as the air isthereafter moved outwardly and downwardly along the walls of the chamberby convection, it is dried by con densation of moisture therefrom ontothe inner surfaces of the chamber walls, the air thus being capable ofevaporating additional moisture from the dishes as it again flowsupwardly therethrough.

Another object is to provide a method of and apparatus for drying disheswherein the heating of the air in the dish chamber is terminated after apredetermined time interval, whereupon the air convection in the chamberis maintained by the heat stored in the dishes themselves until suchtime as the drying operation is completed. In other words, during theinitial portion of the rying operation wherein heat is supplied to theair in the chamber by the heating means to produce the hereinbeforediscussed circulation by convection, the dishes are heated to anelevated temperature and, after termination of the heating by theheating means, the heat stored in the dishes is transferred to the aircirculating in the chamber each time such air passes 'over the dishes tocontinue the circulation in the chamber by convection. Thos, the heatingmeans needs to be energized for only a portion of the drying operation,which is an important feature.

Another object in connection with certain embodiments of the presentinvention is to maintain the chamber walls at a temperature below thetemperature of the air circulating in the chamber by exposing the outersurfaces of the chamber walls to the ambient air. Under all but the mostunusual atmospheric conditions, the temper,"- ture of the ambient airwill be well below the temperature of the air circulating in the dishchamber so that the chamber walls will be maintained at a temperaturesuiiiciently below the temperature of the air circulating in the chamberto produce the desired condensation of moisture on the inner surfaces ofthe chamber walls.

.ln many instances, adequate cooling of the walls of the closed chambercontaining the dishes is attained merely by exposing the exteriorsurfaces of such walls to the ambient air in the room or other area inwhich the dishwasher is d'sposed. In other words, adequate cooling undersuch conditions is frequently attained by radiation from the chamberwalls, by thermal convection of the ambient air thereover, and by normalair circulation in the room or other area.

However, I prefer to employ forced air circulation over the exteriorsurfaces of the chamber walls and, to this end, an important object ofthe invention is to provide a dishwasher wherein the closed chambercontaining the dishes is enclosed by an outer housing through whichambient air is propelled.

More particularly, an object is to provide a dishwasher having an outerhousing formed by outer walls which are spaced outwardly from the wallsof the dish chamber, hereinafter referred to also as inner walls, toprovide between such inner and outer walls a space which surrounds thedish chamber, ambient air being propelled through such space by a fan,or the like, to maintain the temperature of the inner walls below thetemperature of the air circulating in the chamber. A related object isto provide a dishwasher wherein the space through which the ambient airis propelled completely surrounds the closed chamber containing thedishes. More specifically, an object in this connection is to provide adoor for access to the closed chamber which is defined by certain ofsaid inner and outer walls, such inner and outer walls also being spacedapart to permit propelling ambient air therebetween.

Another object of the invention is to provide a dishwasher wherein thewalls of the closed chamber containing the dishes are cooled by means ofa liquid, preferably water from the normal household or other cold watersupply, applied to the chamber walls either externally or internallythereof. lf the chamber walls art cooled by water applied externallythereto, the moisture evaporated from the dishes in the mannerhereinbefore discussed is condensed on the inner surfaces of such wallsin the same manner as for the cases mentioned in which the chamber wallsare cooled by the ambient air. For the case in which the water isapplied to the chamber walls internally thereof, the cooling water ispreferably spread over the interior surfaces of such walls in relativelythin sheets, whereupon the moisture evaporated from the dishes condenseseither on the interior surfaces of the chamber walls, or directly on thewater sheets, the cooling water being drained ofi along with thecondensate.

Another object is to facilitate drying of the dishes by minimizing theamount of water which must be evaporated and subsequently condensed inthe manner hereinbefore described. More particularly, an object of theinvention is to minmize the amount of water from the nal rinse whichhangs up on various components of the dishwasher, such as the racks forsupporting the dishes, the upper wall of the chamber containing thedishes, and the like. More particularly, an object in this connection isto minimize water hang up on the dish racks by eliminating, orsubstantially eliminating, horizontal elements from the dish racks, arelated object being to make the dish racks of zig zag construction sothat all, or substantially all, elements thereof are sloping orvertical. With this construction, the dish racks are provided withnumerous apices to which water droplets may drain and fall off, therebyminimizing the number of water droplets retained by the dish racks forsubsequent evaporation. In connection with the upper wall of the dishchamber, an object is to make such upper wall with a sloping surface, orsloping surfaces, to minimize water droplet hang up. Other objects inthis connection are to minimize horizontal surfaces on which waterdroplets can hang up throughout the entire interior of the dish chamber.

Another object of the invention is to provide a dishwasher the operatingcycle of which is timer controlled so that the washing, rinsing anddrying operations are carried out automatically, it being understood,however, that certain features of the invention may be embodied 4 inmanually operated or semiautomatic dishwashers as well.

Another object is to provide a timer-controlled dishwasher having athermostat or thermostat means which responds to the temperature withinthe dish chamber, and having means controlled by the thermostat forinterrupting operation of the timer until the temperature of the waterutilized for the final rinsing of the dishes is up to a preselectedvalue, the hereinbefore discussed heating means for circulating the airin the dish chamber during drying also being utilized to heat the wateremployed during the washing and rinsing operations. After thetemperature of the water utilized for the final rinse is up to thepreselected value, the timer is re-energized and thereafter againcontrols the operating cycle, the control of the operating cycle beingtaken away from the timer only when it is necessary to heat the finalrinse water up to the preselected value. This feature of the inventionprovides a sterilizing rinse regardless of the temperature of the wateravailable to the dishwasher,

Vand is important to the drying operation since it insures that thedishes are heated to the preselected temperature of the final rinsewater before the drying operation is initiated, thereby expediting thedrying operation.

An important object of the invention is to utilize a single thermostatfor regulating both the temperature of the washing and rinsing waterduring the washing and rinsing operations and for regulating thetemperature of the air utilized to dry the dishes during the dryingoperation. More particularly, an object is to utilize a singlethermostat for limiting the temperature of the washing and rinsing waterto one preselected value and for limiting the temperature of the airutilized to dry the dishes to a higher preselected value. Consideringhow the foregoing is accomplished, the thermostat is located in a sumpat the bottom of the dish chamber below the normal water level therein.Thus, the thermostat limits the water temperature to the preselectedvalue for which the thermostat is designed. During the drying operation,the thermostat limits the air temperature at the bottom of the dishchamber to the same preselected value, but the air in the dish chamberat the level of the dishes therein will be at a higher value due to thefact that the heated air rises in the dish chamber. For example, if thethermostat limits the temperature of the washing and rinsing water toF., and limits the temperature of the air at the bottom of the dishchamber to 160 F. during drying, the temperature of the air in the upperportions of the dish chamber in the vicinity of the dishes will be at ahigher preselected value, e.g., F. to 190 F. Thus, the same thermostatis utilized to maintain the temperature of the washing and rinsing waterat one preselected value and is utilized to maintain the drying airtemperature in the vicinity of the dishes at a higher preselected value,which is an important feature of the invention.

The foregoing objects, advantages and features of the present invention,together with various other objects, ad-

vantages and features thereof which will become apparent, may beattained with the exemplary embodiments of the invention illustrated inthe accompanying drawings and described in detail hereinafter. Referringto the drawings:

Fig. l is a vertical sectional view of one embodiment of the presentinvention;

Fig. 2 is a horizontal sectional view taken along the broken line 2-2 ofFig. l;

Fig. 3 is a simplified diagrammatic view of a control circuit for theinvention;

Fig. 4 is a vertical sectional view of an alternative dish chamberconstruction; and

Fig. 5 is a vertical sectional view of an alternative dish chambercooling means.

Referring particularly to Figs. l and 2 of the drawings,

designated generally by the numeral and includes au inner, closed, dishchamber 12 having upper, lower and side walls. The dish chamber 12 isenclosed by an outer housing or cabinet 16 the walls of which are spacedoutwardly from the walls of the dish chamber to provide a space 20completely surrounding the dish chamber. A doorway 22 provides access tothe interior of the chamber 12, this doorway being closed by a door 24shown as hinged to the structure of the dishwasher 10 at 26.Interconnected walls 28 and 30 of the dish chamber 12 and the cabinet 16form the door 24, the walls 28 and 30 being spaced apart to make thespace 20 coeXtensive with the door so that the space 26 completelysurrounds the dish chamber 12 as hereinbefore indicated. The door 24 isshown as carrying a sealing strip 32 which is engageable with the dishchamber 12 along at least the sides and the top of the doorway 22 so asto provide means for sealing the dish chamber against the escape ofwater during washing and rinsing operations to be described. In theparticular construction illustrated, the lower edge of the wall 28extends downwardly into a sump 34 forming the lower wall of the dishchamber so that a water seal is provided along the lower edge of thedoor 24 to prevent the escape of water during the washing and rinsingoperations. EX- cept for the doorway 22, which is sealed in the mannerhereinbefore described, and some means, not shown, for introducing waterinto the dishwasher, the dish chamber 12 is completely closed.

Located within the dish chamber 12 adjacent the bottom thereof is awashing-duid impelling means 36, the washing iluid preferably beingwater with or without such additives as detergents, water softeners, andthe like, as is well known in the art. In the particular constructionillustrated, the impelling means 36 takes the form of a rotary sprayingdevice for spraying the washing fluid upwardly throughout the interiorof the dish chamber 12 and over any dishes therein to be washed and/orrinsed, the dishes being suitably supported in the chamber 12, as onsuitable racks 37 which are shown fragmentarily. The impelling means 36may take the form of a spraying device of the reaction type, or it maytake the form of a positively driven spraying device, or the like. Inthe particular construction illustrated, the impelling means 36 is areaction-type spraying device which is supplied with washing fluid by apump 38 communicating with the sump 34, the pump being driven by anelectric motor 40 disposed below the dish chamber 12 in a portion of thespace 20 between the chamber 12 and the cabinet 16. The washing uid maybe introduced into the chamber 12 in any suitable manner, not shown, asby way of a valve, not shown, controlled by a solenoid 41, Fig. 3. Thewater may be drained from the dish chamber 12 in any suitable manner bya draining means 42, Figs. l and 3, the draining means being shown inFig. l as including a solenoid 43 for actuating a drain valve, notshown.

Centrally located at the bottom of the dish chamber 12 is a heatingmeans 44 shown as comprising an electrical heating element 46 carried bythe sump 34 and controlled by a thermostat 47 carried by the sump at thebottom of the dish chamber, the thermostat being so located relative tothe heating element 46 that direct radiation from the heating clement tothe thermostat is minimized. The heating means 44, in addition toperforming a heating function in connection with the washing and rinsingwater and the drying air, also serves as a means for circulating thedrying air within the dish chamber 12 throughout this chamber byconvection in a pattern somewhat as indicated by the arrows 4g. In otherwords, the air heated by the heating means 44 rises centrally of thedish chamber 12 and then flows outwardly and downwardly along the innersurfaces of the walls of the dish chamber, to be again heated by theheating means 44 and again caused to rise centrally of the chamber in acontinuous ow pattern.

As more fully discussed hereinafter, the air circulating in the dishchamber 12 during the drying operation is relieved of moisture carriedthereby by condensation of such moisture on the inner surfaces of thewalls of the dish chamber. In order to produce such condensation, thewalls of the dish chamber 12 are maintained at a temperature below thatof the air circulating in the dish chamber. The walls of the dishchamber 12 may be cooled either with the ambient air, or, as discussedhereinafter, with a liquid such as water from the normal household orother cold water supply. One way of cooling the walls of the dishchamber 12 with ambient air is to merely expose the dish chamber to theambient air, in which case the cabinet 16 would not be utilized. Undersuch conditions, cooling of the dish cha-mber walls would be attained byradiation therefrom into the ambient air, or by conduction to theambient air, such conduction being enhanced by thermal convection of theamb-ient air over the external surfaces of the dish chamber walls and bynormal air circulation in the room or other area in which the dishwasheris located.

However, as hereinbefore indicated, I prefer to maintain the temperatureof the dish chamber walls below the temperature of the drying aircirculating in the dish chamber by forced air circulation over theexternal surfaces of the dish chamber walls. To this end, atmosphericair is circulated throughout the space 2G between the dish chamber 12and the outer housing or cabinet 16 by an air propelling means Sti shownas including a fan 52 driven by an electric motor S4. The fan 52 drawsambient air in through an inlet 56 in the cabinet 16 and propels suchair throughout the space 20 between the chamber 12 and the cabinet, theair escaping from the cabinet through outlet openings 58, all asindicated by the arrows 66. lt will be noted that the ambient airpropelled by the fan 52 also tiows through the door 24, i.e., betweenthe walls 2S and 30 forming the door, such air escaping through openings62 at the top of the door.

The foregoing completes a general description of the structure andoperation of the dishwasher of the invention and the manner in which thedishwasher is timer controlled will now be considered before consideringthe operation of the dishwasher in detail. Referring to Fig. 3 of thedrawings, the control circuit illustrated includes parallel circuits 71,'72, 73, 74 and 75 all controlled by a switch 76, the latter cooperatingwith the door 24, in a manner not shown, to energize the control circuitonly when the door is closed. The circuits 7i., 72, 73, 74 and 75respectively include switches 81, 82, 83, 84 and 85 controlled bydiagrammatically-shown cams 91, 92, 93, 94 and 95, the cams being drivenby a timer motor 96 in the circuit 73. The circuit 71 includes thedraining means 42 and the fan 52 and the cam 91 closes the switch 81 toenergize these elements whenever water is to be drained from the dishchamber 12 and throughout the entire drying operation. The circuit 74includes the pump motor 40, and the cam 94 closes the switch 84 toenergize the pump motor during the various washing and rinsingoperations. The circuit 75 includes the solenoid 41 and the cam 95closes the switch to energize the solenoid 41 so as to open the tillvalve to admit water to the dish chamber 12 at the proper points in theoperating cycle.

Considering the circuits 72 and 73, the circuit 72 includes thethermostat 47 and the heating element 46, as well as a signal light 97in parallel with the heating element. The circuit "13 includes the timermotor Q6, as well as a signal light 9S in parallel therewith. Thethermostat 47 includes a switch element engageable with a contact 99 ora contact 10), the parallel circuit 72 being completed through thethermostat and the switch 32 when the contact 99 is engaged, and theparallel circuit 73 being energized through the thermostat when thecontact 100 is engaged, the contact being connected to the circuit 73between the timer motor 96 and the switch S3 to energize the timer motorwhen the switch 83 is open.

Considering the operation of the dishwasher 10, the dishes to be washedare placed on the racks 37 in the dish chamber 12 and the door 24 isclosed, thereby closing the switch 76 to energize the control circuit.The timer, comprising the timer motor 96 and the cams and switchescontrolled thereby, then causes the dishwasher to perform a series ofwashing and rinsing operations, including a preliminary rinse prior towashing if desired, in a manner which need not be discussed in detailherein, the various elements performing their intended functions in amanner which will be apparent. Only the final rinsing operation and thedrying operation, and the relationship therebetween, will be consideredin detail herein.

After filling the sump 34 for the final rinsing operation, which may bethe only rinsing operation, the cam 93 opens the switch 83 tode-energize the timer motor 96, which remains de-energized until thetemperature of the final rinse water has been increased, if necessary tothe preselected value, e.g., 160 F., by the heating element 46. The cam92 closes the switch 82 at this point in the operating cycle and thethermostat 47 engages the contact 99. At this point in the operatingcycle, the cam 91 opens the switch 81 to deenergize the draining means42 and the fan 52, the cam 95 opens the switch 85 to de-energize thefill solenoid 41, and the cam 94 opens the switch 84 to de-energize thepump motor 40. As soon as the heating element 46 has heated the water inthe dish chamber 12 up to the preselected value, the thermostat 47disengages the contact 99 to interrupt the circuit through the heatingelement, and engages the contact 100 to re-energize the timer motor 96,even though the switch 83 is open. At this point, the cam 94 closes theswitch 84 to energize the pump motor 40. A slight rotation of the cam 93by the timer motor 96 recloses the switch 83 to insure continuedoperation of the timer motor 96 even though the thermostat 47subsequently interrupts the circuit therethrough, the switch 83 normallycontrolling the timer motor 96 being closed throughout the entireoperating cycle, except for the interruption discussed during theinterval while the temperature of the final rinse water is beingincreased to the preselected value.

By delaying the operating cycle in the foregoing manner to insure thatthe final rinse water is up to the desired preselected value, thoroughpreheating of the dishes by the final rinse water is insured to expeditesubsequent drying thereof, which is an important feature of theinvention.

yConsidering now the drying operation, after the final rinse has beencompleted, the cam 94 opens the switch 84 to de-energize the pump motor40 and the cam 91 closes the switch 81 to energize the draining means 42and the fan motor 52, the latter circulating air through the space 20between the dish chamber 12 and the cabinet 16 as hereinbeforediscussed. The cam 95 holds the switch 8S controlling the ll solenoid 41open, and the cam 93 maintains the switch 83 closed, as hereinbeforedisoussed, to energize the timer motor 96. During an initial portion ofthe drying operation, the cam 92 closes the switch 82 to maintain theheating element 46 in operation under the control of the thermostat 47,which limits the air temperature at the bottom of the dish chamber 12 tothe preselected value for which the thermostat is designed, the air inthe dish chamber in the vicinity of the dishes being at a substantiallyhigher temperature for the reasons hereinbefore discussed During theinitial portion of the drying cycle, which may be of the order ofmagnitude of one-third the length of the complete drying cycle, theheating means 44 is in operation, as indicated above, and, under thecontrol of the thermostat 47, maintains the air within the dish chamber12 in the vicinity of the racks 37 at a predetermined value, such as 180F. to 190 F., for example, by maintaining the temperature of the air atthe bottom of the dish chamber at a lower temperature, such as F. Theheating of the air in the chamber 12 by the heating means 44 causes theair to circulate by convection approximately as indicated by the arrows48 and as hereinbefore described. The air in the chamber 12, in passingupwardly through the dishes therein, evaporates water therefrom andcarries such water upwardly to the top of the chamber. At the same time,the fan 52, which is in operation throughout the entire drying cycle,propels atmospheric air through the space 20 surrounding the chamber 12,the atmospheric air, under all normal conditions, being at a temperaturevery considerably lower than the temperature of the air within thechamber 12. As a consequence, the atmospheric air propelled through thespace 20 maintains the chamber walls at a temperature lower than the airtemperature within the chamber so that, as the air within the chamberflows outwardly and downwardly along the chamber walls, the moisturepreviously evaporated from the dishes within the chamber is condensed onthe chamber walls, such condensed moisture draining downwardly to thesump 34 and being disposed of by the draining means 42, which also is inoperation continuously during the entire drying cycle. The moisturecondensed out of the air moving over the chamber walls in this mannerreduces the humidity thereof so that, when the air is reheated by theheating means 44 and again passed upwardly through the dishes, it iscapable of absorbing more vmoisture therefrom, additional moisture againbeing condensed from the air as it again moves over the chamber wall-scooled by circulation of atmospheric air through the space 20.

it has been found that the dishes may be dried effectively and in arelatively short period of time by energizing the heating means 44during only a part of the complete drying cycle, i.e., during thehereinbefore rcferred to initial portion of the drying cycle. During thefinal portion of the drying cycle, the heating means 44 may bede-energized, by designing the cam 92 to open the switch 82 at theproper point, whereupon the heat stored in the dishes during the initialportion of the drying cycle maintains the desired air circulation withinthe chamber 12 by convection, the heat stored in the dishes beingtransferred to the air to cause the air to continue to circulate in thechamber 12 and evaporate moisture from the dishes in the mannerhereinafter discussed. Consequently, it is necessary to energize theheating means 44 during only part of the complete drying cycle, which isan important feature.

It has been found that complete drying of the dishes will take placewith the foregoing procedure in a period of time of only about l5 to 20minutes if atmospheric air is propelled through the space 20 at a rateand under temperature conditions such that the temperature of thechamber walls is maintained at a value of approximately 20 F. below theair temperature in the chamber. in other words, even with a relativelysmall temperature differential between the chamber walls and the air inthe chamber 12, drying of the dishes in a satisfactorily short period oftime is attained. Of course, if a larger temperature differential ismaintained, the drying time may be reduced.

The present invention thus attains the principal objects hereinbeforediscussed of maintaining the degree of sterility and cleanlinessobtained during the washing and rinsing operations, and of avoiding thedischarge of moisture into the room or other area in which thedishwasher is located, both of theseI objects being attained by avoidingdrying of the dishes by circulating ambient air from the room thereover.Another important result attained by the drying method of the presentinvention is that much more effective drying of the dishes is attainedas compared to drying by circulating ambient air from the room over thedishes. For example, heating the air in the dish chamber 12 from atemperature of 157 F.

k2,918,0ee

to a temperature of 177 F. provides a drying capacity, i.e., an abilityto hold moisture in the vapor phase, of 31/2 times the drying capacityof air heated from 80 F. to 125 F. in accordance with prior practice. Inother words, the present invention provides a much greater dryingcapacity with a much smaller drying-air temperature increase, which isan important feature.

As hereinbefore indicated, a feature of the dishwasher of the inventionis that the amount of water which must be evaporated from the walls ofthe dish chamber 12 and from elements therein is minimized by minimizingwater droplet hang up. ln connection with the dish racks 37, this isaccomplished by making all, or substantially all, of the elementsforming the racks nonhorizontal. Referring to Fig. l of the drawings, itwill be seen that the dish racks 37 are made up of vertical andgenerally horizontal wires, all of the generally horizontal Wires beingof zig zag shape so as to provide sloping portions 110 down which thewater may drain to apices 111. Most of the water droplets fall from theapices E11 and thus do not need to be evaporated from the dish racks 37,which is an important feature. Horizontal surfaces on which waterdroplets can hang up are eliminated insofar as possible throughout theremaining elements in the dish chamber 12 and throughout the walls ofthe dish chamber 12 itself. For example, referring to Fig. l of thedrawings, the upper wall of the dish chamber 12 is more or less domeshaped and includes sloping surfaces 114 extending from the center ofthe upper wall to the sides of the dish chamber. Referring to Fig. 4 fthe drawings, illustrated therein is an alternative upper wall for thedish chamber 12 which attains substantially the same results but whichreduces the height of the dish chamber. In Fig. 4 of the drawings, theupper wall of the dish chamber is provided with a plurality of slopingsurfaces 116 down which water droplets may drain to the lowest pointsthereon, thereby minimizing water droplet hang up. Thus, throughout thedish chamber 12, water droplet hang up is minimized to minimize theamount of water which must be evaporated during the drying operation,which is an important feature.

As hereinbefore indicated, while embodiments of the invention whereinthe walls of the dish chamber 12am cooled during the drying operation bythe ambient air have been disclosed, the walls of the dish chamber mayalso be cooled with a liquid, such as water from the normal household orother cold water supply. The dish chamber walls may be cooled byapplying cold water externally thereto, or internally thereto, asillustrated in Fig. of the drawings. Referring thereto, illustrated is adish chamber 120 having at the top thereof a water distributing manifold121 provided with orifices 122 which are directed toward the side wallsof the dish chamber in such a manner as to spread thin sheets of wateron the inner surfaces of the side walls of the dish chamber. The watersheets thus maintain the walls of the dish chamber at a considerablylower temperature than the drying air within the dish chamber, andcondensation of moisture from the drying air in the dish chamber takesplace either on the walls of the dish charnber 120, or directly on thewater sheets on the inner surfaces of the walls. The cooling water usedin this manner is drained olf by the draining means 42, along with thecondensate.

Although I have disclosed exemplary embodiments of the invention, itwill be understood that various changes, modifications and substitutionsmay be incorporated in such embodiments without departing from thespirit of the invention as defined by the patent claims hereinafterappearing.

I claim as my invention:

1. In a dishwasher, the combination of: a closed chamber adapted toreceive therein dishes to be washed, rinsed and dried and includingupright walls having inner and outer surfaces; means for washing dishesin said chamber; means for rinsing dishes in said chamber; and means fordrying dishes in said chamber without discharging water vapor into thesurrounding atmosphere, said drying means including air recirculatingmeans for recirculating air confined in said chamber rst upwardly overdishes therein and then downwardly over said inner surfaces of saidupright walls of said chamber, and said drying means including anenclosure spaced outwardly from said chamber and providing between saidchamber and said enclosure an air passage bounded by said upright wallsof said chamber, said enclosure having an air inlet connecting said airpassage to the atmosphere adjacent the bottom of said air passage andhaving an air outlet connecting said air passage to the atmosphereadjacent the top of said air passage so that said air passage conductsatmospheric air from said inlet upwardly over said outer surfaces ofsaid upright walls of said chamber to said outlet to maintain thetemperature of said upright walls of said chamber below the temperatureof the air being recirculated in said chamber, whereby moistureevaporated from dishes in said chamber by the air being recirculatedtherein is conveyed to said inner surfaces of said upright walls of saidchamber by the air being recirculated in said chamber to be condenseddirectly on said inner surfaces of said upright walls. l

2. In a dishwasher having a front, the combination of: a closed chamberadaptedl to receive therein dishes to be washed, rinsed and dried andincluding upright walls having inner and outer surfaces; means forwashing dishes in said chamber; means for rinsing dishes in saidchamber; and means for drying dishes in said chamber' withoutdischarging Water vapor into the surrounding atmosphere, said dryingmeans including air recirculating means for recirculating air confinedin said chamber first upwardly over dishes therein and then downwardlyover said inner surfaces of said upright walls of said chamber, and saiddrying means including an enclosure spaced outwardly from said chamberand providing between said chamber and said enclosure an air passagebounded by said upright walls of said chamber, said enclosure having atthe front of said dishwasher an air inlet connecting said air passage tothe atmosphere adjacent the bottom of said air passage and having at thefront of said dishwasher an air outlet connecting said air passage tothe atmosphere adjacent the top of said air passage so that said airpassage conducts atmospheric air from said inlet upwardly over saidouter surfaces of said upright walls of said chamber to said outlet tomaintain the temperature of said upright walls of said chamber below thetemperature of the air being recirculated in said chamber, wherebymoisture evaporated from dishes in said chamber by the air beingrecirculated therein is conveyed to said inner surfaces of said uprightwalls of said chamber by the air being recirculated in said chamber tobe condensed directly on said inner surfaces of said upright walls.

3. A dishwasher according to claim 2 wherein one of said upright wallsof said chamber is a front wall at the front of said dishwasher andwherein said dishwasher includes a door movable relative to said chamberand said enclosure from a closed position to an open position to provideaccess to the interior of said chamber, said door having an inner wallwhich forms said front wall of said chamber and having an outer wallwhich forms a front wall of said enclosure and which is connected to andspaced fro'm said inner wall of said door, the space between said innerand outer walls of said door forming part of said air passage when saiddoor is in said closed position and conducting atmospheric air from saidinlet upwardly to said outlet when said door is in said closedpo'sition.

4. In a dishwasher having a front, the combination of: a chamber adaptedto receive therein dishes to be washed, rinsed and dried and having atthe front thereof a doorway for access to the interior of said chamber;a door movable relative to said chamber between a closed positionwherein it closes said doorway and an open position, said door having aninner wall which forms a front wall of said chamber when said door is insaid closed position, said door having an outer wall spaced from andconnected to said inner wall thereof, the space between said inner andouter walls of said door having upper and lower ends communicating withthe atmosphere when said door is in said closed position so as toconduct atmospheric air over the outer surface of said inner wall ofsaid door to cool said inner wall of said door; means for washing dishesin said chamber; means for rinsing dishes in said chamber; and airrecirculating means for recirculating air confined in said chamber firstover dishes therein and then over the inner surface of said inner wallof said door when said door is in said closed position, whereby moistureevaporated from dishes in said chamber by the air being recirculatedtherein is conveyed to said inner surface of said inner wall of saiddoor by the air being recirculated in said chamber to be condenseddirectly on said inner surface of said inner wall o'f said door whensaid inner wall of said door is maintained at a temperature below thatof the air being recirculated in said chamber by atmospheric airconducted through the space between said inner and outerwalls of saiddoor.

5. A dishwasher according to claim 2 including fan means within saidenclosure for circulating atmospheric air through said air passage fromsaid inlet upwardly over said outer surfaces of said upright walls ofsaid chamber to said outlet.

6. In a dishwasher, the combination of a closed chamber adapted toreceive therein dishes to be washed, rinsed and dried and includingupright walls having inner and outer surfaces; means for washing dishesin said charnber; means for rinsing dishes in said chamber; and meansfor drying dishes in said chamber without discharging water vapor intothe surrounding atmosphere, said drying means including airrecirculating means for recirculating air confined in said chamber firstupwardly over dishes therein and then downwardly over said innersurfaces of said upright walls of said chamber, said air recirculatingmeans including air heating means centrally located within said chamberadjacent the bottom thereof for recirculating air confined in saidchamber rst upwardly over dishes therein and then downwardly over saidinner surfaces o'f said upright walls of said chamber by convection, andsaid drying means including an enclosure spaced outwardly from saidchamber and providing between said chamber and said enclosure an airpassage bounded by said upright walls of said chamber, Y

said enclosure having an atmospheric air inlet connecting said airpassage to the atmosphere adjacent the bottom of said air passage andhaving an air outlet connecting said air passage to' the atmosphereadjacent the top of said air passage so that said air passage conductsatmospheric air from said inlet upwardly over said outer surfaces ofsaid upright walls of said chamber to said Outlet to maintain thetemperature of said upright walls of said chamber below the temperatureof the air being recirculated in said chamber, whereby moistureevaporated from dishes in said chamber by the air being recirculatedtherein is conveyed to said inner surfaces of said upright walls of saidchamber by the airbeing recirculated in said chamber to be condenseddirectly on said inner surfaces of said upright walls.

7. A dishwasher according to claim 6 including control means for saidair heating means including thermostat means at the bottom of saidchamber for maintaining the air temperature adjacent the top of saidchamber at a higher preselected temperature than the air temperatureadjacent the bottom thereof when said air recirculating means is inoperation during drying of dishes in said chamber.

8. A dishwasher as set forth in claim 6 including timer means forenergizing said air heating means to dry dishes in said chamber and forde-energizing said air heating means after a predetermined time intervalless than that required to completely dry dishes in said chamber,whereby said air recirculation in said chamber is thereafter maintainedby the transfer of heat from dishes in said chamber to the air therein.

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